Long-term performance of Tec vaporizers. Basis for a rational maintenance policy

Dependence of the output of a halothane vaporizer on thymol concentration

The effect of thymol accumulation inside a Fluotec 3 vaporizer on the concentration of halothane delivered by the vaporizer was investigated. The vaporizer output was reduced progressively as the thymol concentration increased, but the reduction was less than that predicted by Raoult's Law. A reduction of 5% in output required an increase in thymol concentration of a factor of 650 compared to the concentration in fresh halothane, while a reduction of 10% required a 1100-fold increase in thymol concentration. The equilibration of the thymol from the wicks throughout the vaporizing chamber was very slow after the vaporizer was drained and filled with fresh halothane; the half-time was 2.7 days.